Method of identifying devices on a bus and apparatus

ABSTRACT

A method of identifying devices on a bus and an apparatus are provided. A method of identifying devices on a bus comprises pooling a plurality of devices connected to a bus, each of the plurality of devices not having uniquely assigned to it a respective unique device identifier (ID) of the bus, selecting, after the pooling, one of the plurality of devices using at least one selection criteria, the at least one selection criteria identifying the one of the plurality of devices uniquely among all of the plurality of devices, and reassigning a unique device ID of the bus to the selected one of the plurality of devices uniquely. An apparatus is configured to carry out the method of identifying devices on a bus.

TECHNICAL FIELD

Embodiments of the invention relate generally to a method of identifyingdevices on a bus and to a corresponding apparatus.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 shows a schematic view of a bus interface and an apparatus inaccordance with an embodiment of the invention.

FIG. 2 shows a state diagram of a dynamic allocation scheme forreassigning a unique device identifier (ID) in accordance with anembodiment of the invention.

FIG. 3 shows a method of identifying devices on a bus in accordance withan embodiment of the invention in a flow diagram.

FIG. 4 shows a method of identifying devices on a bus in accordance withanother embodiment of the invention in a flow diagram.

FIG. 5 shows a method of identifying devices on a bus in accordance withyet another embodiment of the invention in a flow diagram.

In the drawings, like reference characters generally refer to the sameparts throughout the different views. The drawings are not necessarilyto scale, emphasis instead generally being placed upon illustrating theprinciples of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The following detailed description explains exemplary embodiments of thepresent invention. Where applicable the description of a methodembodiment is deemed to describe also the functioning of a correspondingapparatus embodiment and vice versa. The description is not to be takenin a limiting sense, but is made only for the purpose of illustratingthe general principles of the invention. The scope of the invention,however, is only defined by the claims and is not intended to be limitedby the exemplary embodiments described below.

In FIG. 1 a schematic view of a bus interface and an apparatus inaccordance with an embodiment of the invention are shown.

A bus 100 is controlled by a bus controller (master) 110. A number n ofdevices (slaves) D(1) 120, D(2) 130, D(3) 140, . . . , D(n−1) 150 andD(n) 160 are connected to the bus 100. Not shown in the diagram are thedevices numbered 4 to n−2. This is symbolized by the interruption 170 ofthe bus in the drawing. The number n is for example 1, 2, 3, 4, 5, orany other number. For example n may be in the range 10 to 20, in therange 20 to 50 or in the range 50 to 100.

Generally it is desirable to be able to connect as many devices asneeded to a bus without slowing down the operation of the bus too muchand without adding too much complexity or implementation effort.

According to an embodiment of the invention, the following method stepsare performed: pooling a plurality of devices connected to a bus, eachof the plurality of devices not having uniquely assigned to it arespective unique device identifier (ID) of the bus; selecting, afterthe pooling, one of the plurality of devices using at least oneselection criteria, the at least one selection criteria identifying theone of the plurality of devices uniquely among all of the plurality ofdevices; and reassigning a unique device ID (UID) of the bus to theselected one of the plurality of devices uniquely.

According to an embodiment of the invention, an apparatus comprises acontrol unit to pool a plurality of devices connected to a bus, each ofthe plurality of devices not having uniquely assigned to it a respectiveunique device identifier (ID) of the bus; the control unit further toselect one of the pooled plurality of devices using at least oneselection criteria, the at least one selection criteria identifying theone of the plurality of devices uniquely among all of the plurality ofdevices; and the control unit further to reassign a unique device ID(UID) of the bus to the selected one of the plurality of devicesuniquely.

This has the effect that the bus can be operated with a virtually almostunlimited number of devices using a given address space of unique deviceIDs which is only capable of addressing a limited number of devices. Forexample the bus can be operated with a number n of devices using anaddress space providing m unique device IDs where n is larger than m,for example n is much larger than m.

According to an embodiment of the invention, the bus controller 110 hasa control unit 180 configured to pool a plurality of devices D(1) 120,D(2) 130, D(3) 140, . . . , D(n−1) 150 and D(n) 160 connected to the bus100, each of the plurality of devices not having uniquely assigned to ita respective unique device identifier (ID) of the bus; the control unit180 is further configured to select one of the pooled plurality ofdevices using at least one selection criteria, the at least oneselection criteria identifying the one of the plurality of devicesuniquely among all of the plurality of devices; and the control unit 180is further configured to reassign a unique device ID of the bus 100 tothe selected one of the plurality of devices uniquely.

The concept of unique device IDs is explained in more detail in thefollowing. In a bus interface like the one shown in FIG. 1 the deviceson a bus are uniquely identified by an identifier or identification(ID), a unique device ID (UID). Especially in legacy bus specificationsand for interfaces with real time constraints the commands (sequences)on the bus are optimized for length. As a result the address space fordevice ID is strictly limited and cannot be extended, e.g. the number ofbits for the device ID may be 4 bits enabling addressing a maximum of 16devices.

Address space limitations may possibly be overcome by severaltechniques. However, some of these approaches include significantdisadvantages: Adding more bits to the address/ID field is at the costof breaking the sequence/frame structure of the bus specification.Employing parallel busses seems to be feasible in single master systems,while in multi-master systems masters have to be present on all bussesor a router device adding additional complexity and delay is needed.Parallel busses generally demand for additional pads/pins and PCBrouting/wiring resources.

In many bus applications many devices have to be available, but most ofthem are unused at the same time. One aspect of the invention can beillustratively seen in that this fact is employed here.

According to an embodiment of the invention, the limited device IDaddress space is extended by pooling of devices without ID andre-programming of IDs.

According to an embodiment of the invention, device pooling, selectionand dynamic allocation of device IDs are included in this embodiment.Device pooling means that devices not used during some period have nounique device ID, but are put in a pool of devices. Selection means thatdevices in the pool are identified by some measure beyond the shortdevice ID like e.g. manufacturer ID, product ID, serial number, pin/padprogramming, fusing, and the like. Dynamic allocation of device IDsmeans that device IDs can be re-programmed within the limited spaceavailable, for example a free device ID can be allocated, or a(currently) unused device returns its device ID which afterwards isgiven to another device.

Embodiments of the invention have the effect that no change in protocolin terms of bits for the ID is needed. Embodiments of the invention havethe effect that these embodiments may without major changes of the busbe applied to a bus where dynamic allocation is supported by the busspecification. Embodiments of the invention have the effect that noparallel busses are needed and thus resources (pins/pads/PCBarea/wiring) are saved.

Embodiments of the invention may for example be applied to a bus capableof real time operation, the bus being used to control radio frequencyfront end components in a mobile phone or mobile phone system or mobilephone base station. In other words, the bus is configured to addressdevices operating under real time conditions, and these devices may forexample be radio frequency front end components in a mobile phone ormobile phone system or mobile phone base station.

In FIG. 2 a state diagram 200 of a dynamic allocation scheme forreassigning a unique device identifier (ID) in accordance with anembodiment of the invention is shown.

Referring to FIG. 2, in the following an example method forreprogramming of unique ID (UID) is explained with the extensionsnecessary to the procedure.

The state diagram 200 visualizes a dynamic slave address allocationscheme for programming a new UID to a slave. The device (slave) has adefault UID state 205 which is entered e.g. after a reset. In thedefault UID state 205 the device is in the pool of devices not havinguniquely assigned to it a respective unique device identifier (ID) ofthe bus. As long as the selection criteria (vendor, model, category,etc.) do not match to the respective values of the slave (condition 210)the default state 205 is continued which is represented by the loop 215.

A UID is programmed (state transition 220) if all criteria (vendor,model, type, etc.) used to uniquely identify a device match to therespective values of the slave (condition 225). In other words, a uniquedevice ID of the bus is reassigned to the selected one of the pooledplurality of devices uniquely. By this the state “UID=new UID” 230 isentered. As long as the selection criteria (vendor, model, category,etc.) do still match to the respective values of the slave (condition235) the state “UID=new UID” 230 is continued which is represented bythe loop 240.

By issuing a reset by command sequence (reset 245) the UID shall bereturned (state transition 250) to its default value (default UID state205). Similarly, by issuing a reset by signal (reset 255), the UID shallbe returned (state transition 260) to its default value (default UIDstate 205).

As a prerequisite for the dynamic address allocation scheme, thecombination of the used selection criteria (vendor, model, type, etc.)have to be unique. Supported by the wide range of slave devices andvendors for these slave devices an optional programmable UID feature canbe realized.

In the following Table 1 an example is given how the reprogramming ofunique ID (UID) can be done at register level.

Register Address Name Note 0x01 Vendor_id Vendor_id of device 0x02Model_id Model number 0x03 Category Category of device (PA, LNA, switch,. . .) 0x04 Spare Spare but tied to pin, pad, fuse etc. 0x05 UID New UIDto be programmed and used in future read/write cycles to the device

Here some programmable unique slave ID (USID) registers are listed witha register address, a register name and a register description for eachregister. Registers 0x01 to 0x04 select uniquely a device in the pool,while write access to register 0x05 assigns a new UID to be used infuture bus access sequences.

According to an embodiment of the invention, the crucial extension isthat the sequence of reprogramming a UID to a slave does not require theslave to have a unique ID a priori. For example, a reprogrammingsequence (see Table 1) sent to a broadcast (or group slave) ID can beused. Alternatively, one of the available unique device IDs can be usedfor addressing the devices (slaves) in the pool of devices. In thiscase, this UID is assigned to all devices in the pool commonly whichstands in contrast to the usual case, where a UID is always assigned toa single device uniquely.

The slave is identified by the selection criteria, which in this exampleare vendor, model and category. Additionally, the spare bits in register0x04 bound to pin, pad, fuse, or any other identification measure allowdistinguishing otherwise identical devices (e.g. same manufacturer andsame model) on the bus.

In FIG. 3 a method of identifying devices on a bus in accordance with anembodiment of the invention is shown in the flow diagram 300.

At 310 a plurality of devices connected to a bus is pooled, each of theplurality of devices not having uniquely assigned to it a respectiveunique device identifier (ID) of the bus.

At 320, after the pooling, one of the plurality of devices is selectedusing at least one selection criteria, the at least one selectioncriteria identifying the one of the plurality of devices uniquely amongall of the plurality of devices.

At 330 a unique device ID of the bus is reassigned to the selected oneof the plurality of devices uniquely.

According to an embodiment, the method of identifying devices on a busfurther comprises addressing, after the reassigning, the selected one ofthe plurality of devices using the unique device ID.

According to an embodiment, the method of identifying devices on a busfurther comprises withdrawing, before the reassigning, the unique deviceID from another device connected to the bus, the unique device ID havingbeen previously assigned to the other device.

According to an embodiment, the method of identifying devices on a busfurther comprises adding, after the withdrawing, the other device to thepooled plurality of devices.

According to an embodiment, the at least one selection criteria includesone or more of the group consisting of a manufacturer ID, a vendor ID, amodel ID, a category ID, a device serial number, a pin related ID, a padrelated ID and a fusing related ID.

According to an embodiment, the bus is a bus being subject to real timeoperating conditions.

According to an embodiment, the bus is a bus capable of real timeoperation, the bus further to address radio frequency front endcomponents of a mobile phone.

In FIG. 4 a method of identifying devices on a bus in accordance withanother embodiment of the invention is shown in the flow diagram 400.

At 410 one unique device identifier (ID) of a bus is assigned commonlyto each of a plurality of devices connected to the bus.

At 420, after the assigning, one of the plurality of devices is selectedusing at least one selection criteria, the at least one selectioncriteria identifying the one of the plurality of devices uniquely amongall of the plurality of devices.

At 430, another unique device ID of the bus is reassigned to theselected one of the plurality of devices uniquely.

According to an embodiment, the method of identifying devices on a busfurther comprises addressing, after the reassigning, the selected one ofthe plurality of devices using the other unique device ID.

According to an embodiment, the method of identifying devices on a busfurther comprises withdrawing, before the reassigning, the other uniquedevice ID from another device connected to the bus, the other uniquedevice ID having been previously assigned to the other device.

According to an embodiment, the method of identifying devices on a busfurther comprises assigning, after the withdrawing, the unique device IDto the other device in addition to and commonly with each of theplurality of devices.

In FIG. 5 a method of identifying devices on a bus in accordance withyet another embodiment of the invention is shown in the flow diagram500.

At 510 a plurality of devices is connected to a bus, the number ofdevices in the plurality of devices being larger than a maximum numberof available unique device identifiers (IDs) of the bus.

At 520 one or more of the plurality of devices are identified using atleast one identification criteria, the at least one identificationcriteria being a substitute for a respective unique device ID for eachof the one or more of the plurality of devices.

According to an embodiment, the method of identifying devices on a busfurther comprises withdrawing a unique device ID from another deviceconnected to the bus, the unique device ID having been previouslyassigned to the other device.

According to an embodiment, the method of identifying devices on a busfurther comprises reassigning, after the identifying, the unique deviceID to one of the identified one or more of the plurality of devices.

According to an embodiment, the method of identifying devices on a busfurther comprises addressing, after the reassigning, the one of theidentified one or more of the plurality of devices using the uniquedevice ID.

According to a further embodiment of the invention, an apparatuscomprises a control unit configured to carry out a method according toan embodiment of the invention.

According to yet a further embodiment of the invention, any embodimentdefined by one of the claims may be combined with any one or more otherembodiments defined by respective one or more of the other claims.

1. A method of identifying devices on a bus, comprising: pooling aplurality of devices connected to a bus, each of the plurality ofdevices not having uniquely assigned to it a respective unique deviceidentifier (ID) of the bus; selecting, after the pooling, one of theplurality of devices using at least one selection criteria, the at leastone selection criteria identifying the one of the plurality of devicesuniquely among all of the plurality of devices; and reassigning a uniquedevice ID of the bus to the selected one of the plurality of devicesuniquely.
 2. The method as recited in claim 1, further comprising:addressing, after the reassigning, the selected one of the plurality ofdevices using the unique device ID.
 3. The method as recited in claim 1,further comprising: withdrawing, before the reassigning, the uniquedevice ID from another device connected to the bus, the unique device IDhaving been previously assigned to the other device.
 4. The method asrecited in claim 3, further comprising: adding, after the withdrawing,the other device to the pooled plurality of devices.
 5. The method asrecited in claim 1, wherein the at least one selection criteria includesone or more of the group consisting of a manufacturer ID, a vendor ID, amodel ID, a category ID, a device serial number, a pin related ID, a padrelated ID and a fusing related ID.
 6. The method as recited in claim 1,wherein the bus is a bus being subject to real time operatingconditions.
 7. The method as recited in claim 1, wherein the bus is abus capable of real time operation, the bus further to address devicesoperating subject to real time conditions.
 8. The method as recited inclaim 1, wherein the bus is a bus capable of real time operation, thebus further to address radio frequency front end components of a mobilephone.
 9. An apparatus, comprising: a control unit to pool a pluralityof devices connected to a bus, each of the plurality of devices nothaving uniquely assigned to it a respective unique device identifier(ID) of the bus; the control unit further to select one of the pooledplurality of devices using at least one selection criteria, the at leastone selection criteria identifying the one of the plurality of devicesuniquely among all of the plurality of devices; and the control unitfurther to reassign a unique device ID of the bus to the selected one ofthe plurality of devices uniquely.
 10. The apparatus as recited in claim9, the control unit further to address the selected one of the pluralityof devices using the unique device ID.
 11. The apparatus as recited inclaim 9, the control unit further to withdraw the unique device ID fromanother device connected to the bus, the unique device ID having beenpreviously assigned to the other device.
 12. The apparatus as recited inclaim 11, the control unit further to add the other device to the pooledplurality of devices.
 13. A method of identifying devices on a bus,comprising: assigning one unique device identifier (ID) of a buscommonly to each of a plurality of devices connected to the bus;selecting, after the assigning, one of the plurality of devices using atleast one selection criteria, the at least one selection criteriaidentifying the one of the plurality of devices uniquely among all ofthe plurality of devices; and reassigning another unique device ID ofthe bus to the selected one of the plurality of devices uniquely. 14.The method as recited in claim 13, further comprising: addressing, afterthe reassigning, the selected one of the plurality of devices using theother unique device ID.
 15. The method as recited in claim 13, furthercomprising: withdrawing, before the reassigning, the other unique deviceID from another device connected to the bus, the other unique device IDhaving been previously assigned to the other device.
 16. The method asrecited in claim 15, further comprising: assigning, after thewithdrawing, the unique device ID to the other device in addition to andcommonly with each of the plurality of devices.
 17. A method ofidentifying devices on a bus, comprising: connecting a plurality ofdevices to a bus, the number of devices in the plurality of devicesbeing larger than a maximum number of available unique deviceidentifiers (IDs) of the bus; and identifying one or more of theplurality of devices using at least one identification criteria, the atleast one identification criteria being a substitute for a respectiveunique device ID for each of the one or more of the plurality ofdevices.
 18. The method as recited in claim 17, further comprising:withdrawing a unique device ID from another device connected to the bus,the unique device ID having been previously assigned to the otherdevice; and reassigning, after the identifying, the unique device ID toone of the identified one or more of the plurality of devices.
 19. Themethod as recited in claim 18, further comprising: addressing, after thereassigning, the one of the identified one or more of the plurality ofdevices using the unique device ID.